25% DLI might be a good argument for 24/0 ...
At some point the lost DLI would outweigh whatever benefits a dark cycle provides. I wouldn't pretend to be able to say where that break-even point is without a proper sample of data.
This depends on where you live, but an outdoor plant may not be well-adpated for indoor lighting. If you live in a high DLI area, it could have adpated to mitigating excess light per day ... now, with less the leaves are reaching hard for more -- might see some stretch occur if this is the case.
watch out for pests and anything else you may hve brought in with it.